Existence is that which closes off possibilities. It exists because existence is itself.
But the existence of an existence cannot be given within existence itself: it must be given through a set of criteria which defines the terms of existence, and the conditions of existence.
The terms of existence define that which may be said to exist, while the conditions of existence defines that which exists.
Existence is the concretization of the conditions of existence in relation to the terms of existence.
In being that concretization, it identifies (or gives content to) the conditions of existence.
But in order to do so, existence is necessarily in the state of existing to which the concretization refers.
But, in being both the concretized condition of existence, as well as the state of existing, existence relates itself to itself.
Therefore existence is paradox and duality: condition and existence. It is infinite duality.
In other words, when we speak of existence, we refer to the possibility of the conceptualization of the actuality, as well as the actuality through which the possibility of the conceptualization is made meaningful. We have no other examples. But even if we had, we would not call it existence.
So an applied conception of existence creates dualities, depending on the role which the concept performs.
Hence we get absurdities: idealism and materialism are both sides of the same coin, so to speak.
This is the problem engendered in Hegel's quote: All identification is self-identity.
More: all manifested ideas are identified, hence all manifested ideas are self-identifying.
In this sense, duality comes about through the identification process of a concept.
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We could have many universes. Each universe would be a fact referring itself to itself, as a minimum condition.
The world is fundamentally unity, as a necessary condition of its existence, its referring of itself to itself.
Existence is relative when applied, but absolute in conception.
A possible solution to the brain in a vat.
Facts are referred to other facts. A universe of facts is the world of inter-referring facts.
Existence is the act of something referring itself to itself.
It refers the terms of its own existence to the state of its being.
The state of its being is constitutively self-referring.
